Method for monitoring radio equipment for communication between a mobile terminal and a cellular infrastructure with spread spectrum and arrangement for performing said method

ABSTRACT

Parameters for the propagation channels between each mobile terminal ( 14, 14 A,  14 B) and several fixed transceivers ( 13 ) are measured and a report message transmitted to a radio network controller ( 12 ), indicating at least one part of the measured parameters. The radio network controller processes the report messages. The parameters measured for each fixed transceiver are a propagation profile, including at least one propagation path associated with a reception energy and the parameters given in the report messages for at least one transceiver, comprise data on the energetic distribution in the propagation profile, taken into account by the radio network controller in processing.

The present invention concerns the field of digital radiocommunicationswith spread spectrum. It finds its application mainly in cellularnetworks using code division multiple access (CDMA) methods, for examplein third generation networks of the universal mobile telecommunicationsystem (UMTS) type.

The particular feature of spread spectrum techniques is to enableaccount to be taken of multiple propagation paths between thetransmitter and the receiver, which generates an appreciable gain inreception diversity.

A receiver conventionally used for this is the rake receiver whichcomprises a certain number of “fingers” operating in parallel toestimate the digital symbols transmitted. The gain in receptiondiversity results from combining the estimates obtained in the differentfingers of the receiver.

In a spread spectrum CDMA system, the symbols transmitted, usuallybinary (±1) or quaternary (±1±j), are multiplied by spreading codescomposed of samples, called “chips”, the rate of which is greater thanthat of the symbols, in a ratio called the spread factor. Orthogonal orquasi-orthogonal spreading codes are allocated to different channelssharing the same carrier frequency in order to allow each receiver todetect the sequence of symbols intended for it, by multiplying thereceived signal by the corresponding spreading code.

The conventional rake receiver carries out a coherent demodulation basedon an approximation of the impulse response of the radio propagationchannel by a series of peaks, each peak appearing with a delaycorresponding to the propagation time throughout the length of aparticular path and having a complex amplitude corresponding to theattenuation and to the signal phase shift throughout the length of thatpath (instantaneous realization of fading). By analyzing severalreception paths, that is by sampling on several occasions the output ofa filter matched to the channel's spreading code, with delayscorresponding respectively to those paths, the rake receiver obtainsmultiple estimates of the transmitted symbols, which are combined toobtain a gain in diversity. The combination can mainly be effectedaccording to the method known as “maximum ratio combining” (MRC) whichweights the different estimates according to the complex amplitudesobserved for the different paths. To enable this coherent demodulation,pilot symbols can be transmitted with the information symbols for theestimate of the impulse response in the form of a succession of peaks.

Usually, in cellular systems, the fixed transceiver serving a given cellalso transmits a marker signal on a pilot channel to which is allocateda determined pilot spreading code. This pilot code is communicated tothe mobile terminals located in the cell or nearby, by means of systeminformation transmitted by the base stations. The terminals takemeasurements of the power received on the pertinent pilot codes. Thesemeasurements enable mobiles on standby to identify the best cell to useif they have to make a random access. They also are used to identify,during a communication, the cell or cells with which the radio linkconditions are the best for making an intercell communication transfer(“handover”) if necessary.

Another particular feature of spread spectrum CDMA systems is theability to support a macrodiversity mode. Macrodiversity consists inenvisaging that a mobile terminal can simultaneously communicate withdistinct fixed transceivers of an active set. In the downlink direction,the mobile terminal receives the same information several times. In theuplink direction, the radio signal transmitted by the mobile terminal iscaptured by the fixed transceivers of the active set to form differentestimates subsequently combined in the network.

Macrodiversity procures a reception gain which improves the performanceof the system by combining different observations of the sameinformation.

It is also used to perform soft handovers (SHO) when the mobile terminalmoves.

The macrodiversity mode leads, in the rake receiver of the mobileterminal, to assigning the fingers allocated to a communication to pathsbelonging to different propagation channels from several fixedtransceivers and usually having different spreading codes.

On the network side, the macrodiversity mode implements a kind ofmacroscopic rake receiver, the fingers of which are located in differenttransceivers. The estimates are combined after channel decoding in abase station if the base station groups together all the transceiversconcerned, or if not, in a controller supervising the base stations.

The macrodiversity mode imposes a certain signaling load in the networkwhen the active set relating to a terminal must be updated. Furthermore,it mobilizes supplementary transmission and reception resources in thebase stations, as well as some bandwidth for the transfer of the data tobe combined in the network. It is therefore judicious to use it onlywhen the reception gain obtained is significant.

This reception gain comes principally from the multiplicity ofpropagation paths taken into consideration. There are many cases inwhich a propagation channel (or a small number of such channels) havesufficiently numerous paths that the addition of one or moresupplementary transceivers to the active set procures only a weak gainin terms of bit error ratio (BER), even though the reception conditionsare correct on the propagation channels between the terminal and thesesupplementary transceivers. In such a case, the macrodiversity linksload the network to no great purpose.

In a CDMA system such as the UMTS, the transmit power over the radiointerface is adjusted through a feedback control procedure in which thereceiver returns power control commands (TPC) to the transmitter to tryto achieve an objective in terms of reception conditions. These TPCcommands consist of bits transmitted at a fairly high rate and theirvalue indicates whether the transmit power should be increased orreduced.

In the case of a communication in macrodiversity, the different fixedtransceivers of the active set receive identical TPC bits from themobile terminal. Respective corrective terms can be taken into accountby these fixed transceivers to balance the transmitted powers. For agiven active set, if a first transceiver generates a large number ofpropagation paths whereas a second generates only a small number ofpaths, it may be preferable to aim for a higher power set-point valuefor the first transceiver than for the second. Otherwise, it may happenthat the gain in macrodiversity brought about by adding the secondtransceiver to the active set is negative.

Since the chip rate is fixed, a high rate physical channel has a lowspread factor and a short symbol duration. If the impulse response ofthis channel comprises paths that are relatively widely spaced overtime, the result is inter-symbol interference which degrades theperformance of the receiver or requires a channel equalizer whichgreatly increases its complexity. It may therefore be advantageous todivide such a channel into two channels of double the spread factor.However, the multiplication of channels with high spread factors is notalways desirable, so it is better to dispense therewith when the channelgenerates almost no inter-symbol interference.

An object of the present invention is to optimize the use of theresources in a radio network with spread spectrum.

So the invention proposes a method of controlling radio resourcesassigned to a communication between a mobile terminal and a cellularradio network infrastructure with spread spectrum, the infrastructurecomprising at least one radio network controller and fixed transceiversserving respective cells. This method comprises the following steps:

-   -   measurement of respective propagation channel parameters between        the mobile terminal and several fixed transceivers, the        measurements comprising the determination, for each fixed        transceiver, of a propagation profile including at least one        propagation path associated with a respective reception energy;    -   transmission to the radio network controller of report messages        indicating at least one part of the measured parameters;    -   processing of the report messages at the radio network        controller.

The parameters indicated in the report messages for at least one fixedtransceiver comprise data dependent on the energy distribution in thepropagation profile, taken into account by the radio network controllerin said processing.

The processing of the report messages for the radio network controllermay comprise a macrodiversity control, that is the determination of anactive set of fixed transceivers relative to the terminal and anactivation of the radio link between the mobile terminal and each fixedtransceiver of the active set.

Consequently, the algorithm of active set management and handovercontrol executed in the radio network controller is not limited toexamining the global reception energies on the different propagationchannels as in conventional systems. It also has information on theenergy distributions in the propagation profiles, which enables itbetter to assess the need to add fixed transceivers to or remove themfrom the active set.

Analogous considerations may apply to other radio resource controlprocedures, particularly to the algorithm for transmission powermanagement of the transceivers of the active set and for power controlexecuted in the radio network controller. In this case, the propagationprofiles enable the radio network controller better to assess the needto increase or reduce the transmission power of the transceivers of theactive set.

The data dependent on the energy distribution in the propagation profileand transmitted to the radio network controller may notably comprise anumber of propagation paths detected between the mobile terminal and thefixed transceiver with a reception energy greater than a threshold. Forexample, if a propagation channel has of itself a sufficiently largenumber of energetic paths, the controller may inhibit the addition ofsupplementary transceivers to the active set or at least make theaddition conditions more severe. In another example, if two transceiversare part of the active set and if each of them has a predominantenergetic path with a comparable attenuation (pathloss), the controllercan balance their transmission powers so that they are equivalent.

Similarly, the data dependent on the energy distribution in thepropagation profile may give an indication on the distribution ofenergetic paths over time. In this case, another example of processingreport messages for the radio controller is to obtain the time shiftbetween the main paths, that is the most energetic paths, on thepropagation channel and to compare it with the duration of a symbol onthe physical channel or channels involved in the communication betweenthe mobile terminal and a fixed transceiver. The radio controller canthen decide to configure the mobile terminal and the fixed transceiverso that they use other physical channels with a format more suited tothe situation with a view to establishing a good compromise between anyinter-symbol interference and a maximum bit rate for the communication.

The data dependent on the energy distribution in the propagation profileand transmitted to the radio network controller may also comprise thevalues of the reception energies respectively associated with one ormore propagation paths detected between the mobile terminal and thefixed transceiver.

The measurements of the propagation channel parameters, or at least someof them, can be downlink measurements taken by the mobile terminal onpilot signals respectively transmitted by the fixed transceivers andformed with determined spreading codes. Some of these measurements mayalso be uplink measurements taken by the fixed transceivers on a pilotsignal included in signals transmitted by the mobile terminal over adedicated channel.

The invention also proposes radio network controllers, mobile terminalsand base stations suitable for the implementation of the above method.

A radio network controller according to the invention, for a cellularradio network infrastructure with spread spectrum, comprising means ofcommunicating with fixed transceivers serving respective cells and withat least one mobile terminal and means of controlling radio resourcesassigned to a communication between the mobile terminal and the cellularnetwork infrastructure. The means of radio resource control comprisemeans for requesting, via the communication means, report messages ofmeasurements of respective propagation channel parameters between themobile terminal and several fixed transceivers, the measurementscomprising the determination, for each fixed transceiver, of apropagation profile including at least one propagation path associatedwith a respective reception energy, means of processing the reportmessages. The parameters indicated in the report messages for at leastone fixed transceiver comprise data dependent on the energy distributionin the propagation profile, taken into account by processing means.

A radiocommunication mobile terminal with spread spectrum according tothe invention comprises:

-   -   a radio interface for communicating with a cellular network        infrastructure comprising at least one radio network controller        and fixed transceivers serving respective cells;    -   means of measuring respective propagation channel parameters        from several fixed transceivers, disposed to determine a        propagation profile for each of said fixed transceivers on the        basis of pilot signals respectively transmitted by said fixed        transceivers, each propagation profile including at least one        propagation path associated with a respective reception energy;        and    -   means of transmitting to the radio network controller report        messages indicating at least part of the measured parameters        including, for at least one fixed transceiver, data dependent on        the energy distribution in the propagation profile.

A base station according to the invention, for a cellular radio networkinfrastructure with spread spectrum, comprising at least one radiotransceiver serving a respective cell, and means of communicating withat least one radio network controller of the cellular networkinfrastructure. Each radio transceiver comprises means of measuringparameters of a propagation channel from a mobile terminal incommunication with the cellular network infrastructure, disposed todetermine a propagation profile on the basis of a pilot signal includedin signals transmitted by the mobile terminal over a dedicated channel,the propagation profile including at least one propagation pathassociated with a respective reception energy and where necessary withthe combination of several reception energies relative to the same pathwhen several receivers are used simultaneously. The means ofcommunicating with the radio network controller comprise means oftransmitting report messages indicating at least a part of the measuredparameters, including data dependent on the energy distribution in thepropagation profile.

Other special features and advantages of the present invention willemerge in the following description of nonlimitative exemplaryembodiments, with reference to the appended drawings, wherein:

FIG. 1 is a diagram of a UMTS network;

FIG. 2 is a diagram showing the organization in layers of communicationprotocols employed on the radio interface of the UMTS network;

FIG. 3 is a block diagram of the transmission part of a radiotransceiver of a UMTS base station;

FIG. 4 is a block diagram of the transmission part of a UMTS mobileterminal;

FIG. 5 is a block diagram of a receiver of a UMTS station;

FIG. 6 is a block diagram of a UMTS radio network controller; and

FIGS. 7 and 8 are flowcharts of algorithms for active set determinationthat can be executed in a radio network controller as shown in FIG. 6.

The invention is described below in its application to a UMTS network,the architecture of which is shown in FIG. 1.

The switches of the mobile service 10, belonging to a core network (CN),are linked on the one hand to one or more fixed networks 11 and on theother hand, by means of an interface known as Iu, to control equipments12, or radio network controllers (RNC). Each RNC 12 is linked to one ormore base stations 9 by means of an interface known as Iub. The basestations 9, distributed over the network's coverage territory, arecapable of communicating by radio with the mobile terminals 14, 14 a, 14b called user equipment (UE). The base stations 9, also called “node B”,may each serve one or more cells by means of respective transceivers 13.Certain RNCs 12 can also communicate with one another by means of aninterface known as Iur. The RNCs and the base stations form an accessnetwork known as a “UMTS terrestrial access network” (UTRAN).

The UTRAN comprises elements of layers 1 and 2 of the ISO model in orderto provide the links required on the radio interface (called Uu), and aradio resource control stage 15A (RRC) belonging to layer 3, as isdescribed in technical specification 3G TS 25.301, “Radio InterfaceProtocol”, version 3.4.0 published in March 2000 by the 3GPP (3rdGeneration Partnership Project). Seen from the upper layers, the UTRANsimply acts as a relay between the UE and the CN.

FIG. 2 shows the RRC stages 15A, 15B and the stages of the lower layerswhich belong to the UTRAN and to a UE. On each side, layer 2 issubdivided into a stage 16A, 16B of radio link control (RLC) and a stage17A, 17B of medium access control (MAC). Layer 1 comprises a stage 18A,18B of encoding and multiplexing. A radio stage 19A, 19B transmits theradio signals based on a stream of symbols supplied by the stage 18A,18B, and receives the signals in the other direction.

There are different ways of adapting the architecture of protocols asshown in FIG. 2 to the hardware architecture of the UTRAN as shown inFIG. 1, and different organizations can usually be adopted to suit thetypes of channels (see section 11.2 of technical specification 3G TS25.401, “UTRAN Overall Description”, version 3.1.0 published in January2000 by the 3GPP). The RRC, RLC and MAC stages are in the RNC 12. Layer1 is for example in the node B 9. A part of this layer may however be inthe RNC 12.

When several RNCs are involved in a communication with a UE, there isusually a serving RNC, called SRNC, which contains the modulespertaining to layer 2 (RLC and MAC) and at least one drift RNC, calledDRNC, to which is linked a base station 9 with which the UE is in radiocontact. Appropriate protocols perform the interchanges between theseRNCs over the Iur interface, for example ATM (“Asynchronous TransferMode”) and AAL2 (“ATM Adaptation Layer No. 2”). These same protocols mayalso be employed over the Iub interface for the interchanges between anode B and its RNC.

Layers 1 and 2 are each controlled by the sublayer RRC, the features ofwhich are described in technical specification TS 25.331, “RRC ProtocolSpecification”, version 4.1.0 published in June 2001 by the 3GPP. TheRRC stage 15A, 15B monitors the radio interface. It also processesstreams to be transmitted to the remote station according to a “controlplan”, as opposed to the “user plan” which is for processing the userdata from layer 3.

The UMTS uses the CDMA spread spectrum technique, meaning that thesymbols transmitted are multiplied by spreading codes consisting ofsamples called “chips” the rate of which (3.84 Mchip/s in the case ofthe UMTS) is greater than that of the symbols transmitted. The spreadingcodes distinguish different physical channels (PhCH) which aresuperimposed on the same transmission resource consisting of a carrierfrequency. The auto- and cross-correlation properties of the spreadingcodes allow the receiver to separate the PhCHs and to extract thesymbols that are sent to it.

For the UMTS in FDD (“Frequency Division Duplex”) mode, on the downlink,a scrambling code is allocated to each transceiver 13 of each basestation 9 and different physical channels used by that transceiver aredistinguished by mutually orthogonal channelization codes. Thetransceiver 13 can also use several mutually orthogonal scramblingcodes, one of them being a primary scrambling code. On the uplink, thetransceiver uses the scrambling code to separate the transmitting UEs,and where appropriate the channelization code to separate the physicalchannels from one and the same UE. For each PhCH, the global spreadingcode is the product of the channelization code and the scrambling code.The spread factor (equal to the ratio between the chip rate and thesymbol rate) is a power of 2 lying between 4 and 512. This factor ischosen according to the symbol rate to be transmitted over the PhCH.

The various physical channels are organized into frames of 10 ms whichsucceed one another on the carrier frequency used. Each frame issubdivided into 15 time slots of 666 μs. Each time slot can carry thesuperimposed contributions of one or more physical channels, comprisingcommon channels and dedicated physical channels (DPCH).

On the downlink, one of the common channels is a pilot channel calledcommon pilot channel (CPICH). This channel carries a pilot signal, ormarker signal, formed on the basis of a predetermined sequence ofsymbols (see technical specification 3G TS 25.211, “Physical channelsand mapping of transport channels onto physical channels (FDD)”, version3.3.0 published in June 2000 by the 3GPP). This signal is transmitted bythe transceiver 13 on the primary scrambling code of the cell, with adetermined channelization code.

FIG. 3 illustrates schematically the transmission part of a fixedtransceiver 13 of a UMTS base station, serving a cell by means of ascrambling code c_(scr). Layer 1 can multiplex Several transportchannels (TrCH) from the MAC sublayer onto one or more PhCHs. The module18A receives the data streams of the downlink TrCHs, from the RNC, andapplies to them the coding and multiplexing operations required to formthe data part (DPDCH) of the DPCHs to be transmitted. These coding andmultiplexing functions are described in detail in technicalspecification 3G TS 25.212, “Multiplexing and channel coding (FDD)”,version 3.3.0 published in June 2000 by the 3GPP.

This data part DPDCH is multiplexed over time, within each 666 ms timeslot with a control part (DPCCH) comprising control information andpredetermined pilot symbols, as shown diagrammatically in FIG. 3 by themultiplexers 20 which form the bit streams of the DPCHs. On eachchannel, a serial/parallel converter 21 forms a complex digital signalthe real part of which consists of the bits of even rank of the streamand the imaginary part of which consists of the bits of odd rank. Themodule 22 applies to these complex signals their respectivechannelization codes c_(ch), which are allocated by a control unit 23.The module 24 weights the resultant signals according to the respectivetransmission powers of the physical channels, determined by a powercontrol process.

The complex signals of the different channels are then summed by theadder 25 before being multiplied by the scrambling code c_(scr) of thecell by means of the module 26. The adder 25 also receives thecontribution of the CPICH, which is not multiplied by a channelizationcode since the channelization coda of the CPICH is constant and equal to1 (technical specification 3G TS 25.213, “Spreading and modulation(FDD)”, version 3.2.0 published in March 2000 by the 3GPP). The basebandcomplex signal s delivered by the module 26 is subjected to a shapingfilter and converted to analog before modulating the carrier frequencyin quadrature phase shift keying (QPSK) and being amplified andtransmitted by the base station.

The different transmission resources of the transceiver 13 are allocatedto the channels by the unit 23 under the control of the RRC stage 15Alocated in the RNC. The corresponding control messages are transmittedby means of a control application protocol of the transceivers, calledNBAP (“Node B Application Protocol”, see technical specification 3G TS25.433, version 4.1.0, “UTRAN Iub Interface NBAP Signalling”, publishedin June 2001 by the 3GPP).

FIG. 4 illustrates schematically the transmission part of a UE. It isassumed here that this UE transmits over a single physical channel. Themodule 27 performs the coding and where necessary the multiplexing ofthe corresponding TrCHs to a physical channel. This forms a real signal(DPDCH) which will be transmitted over a channel I. In parallel, controlinformation and pilot symbols are assembled by a module 28 to form areal signal (DPCCH) which will be transmitted over a channel Q. Thedigital signals of channels I and Q form the real and imaginary parts ofa complex signal the transmission power of which is adjusted by a module29. The resulting signal is modulated by the spreading code of thechannel comprising a scrambling code c_(scr), and represented by themultiplier 30. The complex baseband signal s′ thus obtained thenfiltered and converted to analog before modulating the carrier frequencyin QPSK.

FIG. 5 is a block diagram of a CDMA receiver that may be in the UE forthe downlink or in the node B for the uplink. The receiver comprises aradio stage 31 which performs the analog processing required on theradio signal captured by an antenna 32. The radio stage 31 delivers acomplex analog signal the real and imaginary parts of which aredigitized by the analog-digital converters 33 on respective processingchannels I and Q. On each channel, a filter 34 matched to the shaping ofthe pulses by the transmitter produces a digital signal at the chip rateof the spreading codes.

These digital signals are subject to a bank of matched filters 35. Thesefilters 35 are matched to the spreading codes c_(j) of the channels tobe taken into consideration. These spreading codes c_(j) (products of ascrambling code and where appropriate a channelization code) aresupplied to the matched filters 35 by a control module 40 which managesin particular the allocation of the receiver's resources. On the node Bside, the control module 40 is monitored by the RRC stage 15A of the RNCthrough the NBAP protocol. On the UE side, the control module 40 ismonitored by the RRC stage 15B.

For N physical channels (spreading codes) taken into account, thematched filters 35 deliver N real signals on the I channel and N realsignals on the Q channel, which are supplied to a module 36 forseparation between the data and the pilot signals. For the downlinks,the separation consists in extracting the portions of the time slotscontaining the complex pilot signals transmitted by the node B to supplythem to the channel analysis module 37, the corresponding data beingaddressed to the fingers 38 of the rake receiver. In the case of theuplinks, the separation performed by the module 36 consists inextracting the real pilot signals from the Q channel relative to eachchannel to supply them to the analysis module 37.

For each physical channel, denoted by an integer index i, the analysismodule 37 identifies a certain number of propagation paths, denoted byan index j, on the basis of the portion of the output signal from thematched filter 35 corresponding to the pilot signals, which constitutesa sampling of the channel's impulse response.

There are various possible ways of representing the propagation pathsfor the rake receiver. One method consists in finding the maxima of thechannel's impulse response sampled at the output of the matched filter35, averaged over a period of some hundred milliseconds. Eachpropagation path is then represented by a delay t_(i,j) corresponding toone of the maxima, of instantaneous amplitude a_(i,j). In this case, theprocessing performed in each finger 38 of the rake receiver, allocatedto path j of channel i, consists in sampling the signal received overthe channel i with the delay t_(i,j) and multiplying the result bya_(i,j)*. The selected paths are those for which the reception energiesare the highest, the reception energy following a path j of a channel ibeing equal to the average of |a_(i,j)|².

In another possible representation (see WO01/41382), each propagationpath of a channel i is represented by an eigenvector v_(i,j) of theautocorrelation matrix of the impulse response vector supplied by thematched filter 35. In the processing performed in the finger 38 of therake receiver, sampling with the delay t_(i,j) is then replaced by thescalar product of the output vector of the matched filter 35 times theeigenvector v_(i,j). To estimate the eigenvectors v_(i,j), the analysismodule 37 performs a diagonalization of the autocorrelation matrix,which also supplies the associated eigenvalues λ_(i,j). The eigenvalueλ_(i,j), equal to the mathematical expectation of |a_(i,j)|², representsthe reception energy of the signal on path j of channel i.

The combination module 39 of the rake receiver receives thecontributions of the fingers 38 and, for each channel i, calculates thesum of the respective contributions of the retained paths j, indicatedby the control module 40. The result is the local estimate of theinformation symbols transmitted over channel i.

In the case of a UE receiving downlink signals in macrodiversity mode,that is from several transceivers 13 using different spreading codes,the module 39 may also add up the contributions of the correspondingpropagation channels to obtain the gain in diversity. The combinedestimates that result from this are then submitted to the decoding anddemultiplexing stage (not shown in FIG. 5).

In the case of a base station 9 receiving on several transceivers 13uplink signals from one and the same mobile terminal in macrodiversitymode, the local estimates delivered by the respective combinationmodules 39 of those transceivers 13 are also combined to obtain the gainin diversity.

In the case of an uplink macrodiversity between several base stations 9receiving signals from one and the same mobile terminal, the localestimates delivered by the respective combination modules 39 of thetransceivers are submitted to the decoding and demultiplexing stage (notshown in FIG. 5) to obtain the estimated symbols of the TrCH or TrCHsconcerned. These symbols are transmitted to the SRNC via the Iub (Iur)interface in which they are combined to obtain the gain in diversity.

The corresponding combination module of the RNC 12 is designated by thereference 50 in FIG. 6. This module retrieves from the Iub and/or Iurinterface 51 the symbols of the TrCH from the different base stationsand supplies them the MAC stage 17A after combination. In the downlinkdirection, this module 50 belonging to the physical layer takesresponsibility for transmitting the streams of the TrCHs from the MACstage 17A to the base stations concerned.

FIG. 6 also illustrates schematically an instance 52 of the NBAPprotocol executed at the RNC 12 to control a remote base station. Thedialog between the RRC stage 15A of the RNC and that 15B of a UE isperformed by means of an “RRC connection” managed as described insection 8.1 of technical specification 3G TS 25.331 abovementioned.

The procedures of the RRC protocol comprise measurement proceduresdescribed in section 8.4 of technical specification 3G TS 25.331, whichserve mainly to update the active set for the UEs in macrodiversity (orSHO) as well as to adjust the transmission powers of the transceivers ofthe active set. The measurements expected by the RNC are requested fromthe UEs in “MEASUREMENT CONTROL”, messages, in which are also indicatedthe report modes, for example with a specified periodicity or inresponse to certain events. The measurements specified by the RNC arethen made by the UE which sends them back up on the RRC connection in“MEASUREMENT REPORT” messages (see sections 10.2.17 and 10.2.19 oftechnical specification 3G TS 25.331). These “MEASUREMENT CONTROL” and“MEASUREMENT REPORT” messages are relayed transparently by thetransceivers 13 of the base stations.

Several nonstandardized algorithms can be used by the SRNC to determinethe transceivers 13 of the active set. Examples of them will be examinedlater.

In some cases, these algorithms for determining the active set may takeinto account uplink measurements, taken by the transceivers 13 of thebase stations and sent back up according to the NBAP proceduresdescribed in sections 8.3.8 to 8.3.11 of the abovementioned technicalspecification 3G TS 25.433. The RNC tells the node B the measurements itrequires in a “DEDICATED MEASUREMENT INITIATION REQUEST” message and thenode B sends them back up in a “DEDICATED MEASUREMENT REPORT” message(see sections 9.1.52 and 9.1.55 of technical specification 3G TS25.433).

The modifications of the active set are reported to the UE (controlmodule 40 of the receiver) by means of procedures for updating theactive set in SHO of the RRC protocol, described in section 8.4 oftechnical specification 3G TS 25.331 (“ACTIVE SET UPDATE” message insection 10.2.1).

These modifications also give rise to the transmission of signaling fromthe RNC to the base stations 9 by means of procedures of establishment,addition, reconfiguration and deletion of radio links of the NBAPprotocol, described in section 8 of technical specification 3G TS25.433.

The measurements taken into consideration by the RNC to control theradio links in SHO comprise power measurements taken on the pilotchannels or signals, obtained by a measurement module 41 shown in FIG.5. Various measurements which the mobile terminals and base stationsshould be able to take are listed in technical specification 3G TS25.215, “Physical layer—Measurements (FDD)”, version 3.3.0 published inJune 2000 by the 3GPP. The measurements obtained by the module 41 aretransmitted to the RNC via the control module 40 and the RRC connection(measurement of the UE) or the NEAP protocol (measurement of the nodeB).

For a given channel i, the sum of the eigenvalues λ_(i,j), determined bythe analysis module 37 for the p propagation paths taken intoconsideration (1≦j≦p), represents the global energy received on thechannel, reduced to the duration of a symbol. This energy is called RSCP(“Received Signal Code Power”) in the standard. The analysis module 37also determines, for each channel i, the residual noise power aftertaking into account the p paths. This residual power is called ISCP inthe standard (“Interference Signal Code Power”). The quantity(RSCP/ISCP)×(SF/2) represents the signal-to-interferer ratio (SIR) for adownlink channel, SF designating the channel's spread factor. The SIRequals (RSCP/ISCP)×SF for an uplink channel.

The SIR, evaluated on the pilot symbols transmitted over a dedicatedchannel, is a measurement that the RNC may request from the UE or fromthe node B, and it may, where appropriate, take account of it in themanagement of the active set.

The radio receiver is also capable of measuring the received power inthe bandwidth of the signals around a UMTS carrier. This power, measuredby a module 42 upstream of the matched filters 35, is indicated by thequantity called RSSI (“Received Signal Strength Indicator”).

The UEs in communication monitor in parallel the energies received overthe CPICH channels of the cells belonging to a monitored set comprisingthe active set and a certain number of neighboring cells. These energymeasurements are usually uploaded to the RNC in the “MEASUREMENT REPORT”messages. The quantities uploaded may be the absolute energies(CPICH_RSCP) or, more usually, standardized in relation to the energy ofthe received signal (CPICH_Ec/N0=CPICH_RSCP/RSSI).

To enable a more detailed consideration of the propagation profiles bythe algorithms for active set determination and power control for thisactive set, it is advantageous also to transmit to the RNC datadependent on the energy distribution in the propagation profile. Forthis, particular value choices are provided in the “INTRA-FREQUENCYMEASUREMENT” and “MEASURED RESULTS” information elements (IE) of theabovementioned “MEASUREMENT CONTROL” and “MEASUREMENT REPORT” messagesof the RRC protocol for the downlink measurements and in the “DEDICATEDMEASUREMENT TYPE” and “DEDICATED MEASUREMENT VALUE” IEs of theabovementioned “DEDICATED MEASUREMENT INITIATION REQUEST” and “DEDICATEDMEASUREMENT REPORT” messages of the NBAP protocol for the uplinkmeasurements.

The analysis module 37 of the receiver calculates the eigenvaluesλ_(i,j)=E(|a_(i,j)|²), which are summed over the path index j to obtainthe RSCP of channel i. It therefore has information on the energydistribution in the propagation profile relative to channel i.

The measurement module 41 can retrieve the p values λ_(i,j) and transmitthem to the RNC 12. In a typical embodiment, the physical channelsconcerned will be the CPICHs from the transceivers of the monitored set,the measurements being uploaded by the UE. The uploaded measurements maybe the absolute measurements λ_(i,j), homogeneous to the CPICH_RSCP, orstandardized measurements μ_(i,j)=λ_(i,j)/RSSI, homogeneous to theCPICH_Ec/N0. The measurement module 41 may also, after having identifiedthe main path, that is the one of which the energy is maximal λ_(i max),transmit the values of the other paths relative to that main path, thatis ρ_(i,j)=λ_(i,j)/λ_(i max).

However, it should be noted that the uploaded measurements may also beof the mono-path SIR type, that is proportional to λ_(i,j)/ISCP_(i), andevaluated on the pilot symbols included in the dedicated channels.Furthermore, the measurements dependent on the energy distribution inthe propagation profile may also be measurements taken by the Node B onthe pilot symbols transmitted by the UE over the channel Q.

As a variant, the measurement module 41 may transmit only the valuesλ_(i,j), μ_(i,j) or ρ_(i,j) which exceed a predefined threshold. Thisthreshold is advantageously a parameter that can be adjusted accordingto a configuration command received from the RNC.

Another possibility is for the receiver simply to indicate to the RNChow many paths j give rise to a reception energy λ_(i,j), μ_(i,j) orρ_(i,j) greater than the threshold. This number α_(i), which is ameasurement of the multipath diversity procured by a single transceiver13 for the UE in question, may then be taken into account by thealgorithm for determining and controlling the power of the active set.

It is also possible for the receiver to upload to the RNC an indicationof relative time position for the different paths identified on achannel i. This may involve, for example, the delay t_(i,j) of each pathj, which gives a complete view of the distribution of the paths over aperiod of time. It may also involve the difference between the detectiontimes of two given paths at the receiver. Again, the two paths takeninto account for calculating the time difference to be uploaded to theRNC may be chosen according to different criteria: paths with areception energy λ_(i,j), μ_(i,j) or ρ_(i,j) greater than a threshold(typically the receiver will upload to the RNC the maximum timedifference between two such paths), paths of greatest energy out of allthe paths detected over a fixed period, any pair of consecutive paths,the first path detected (serving as a time reference) and any secondpath etc.

In the case of a cell for which the base station 9 receives on severalantennae indices k (k=1, 2, etc.) uplink signals from one and the samemobile terminal, in space diversity mode, the measurement module 41 cantransmit to the RNC 12 the values corresponding to reception energiesλ_(i,j) calculated by summing the values λ_(i,j ;k) obtained, in themanner previously described, based on the signals respectively capturedby the different antennae. This combination is facilitated by the factthat the delays identifying a path j received by the different antennaeare substantially identical, considering the short distance usuallyseparating these antennae.

To give just one example from those that have been described above, thevalue ρ_(i,j)=λ_(i,j)/λ_(i max) transmitted to the RNC 12 may then bereplaced by the valueρ_(i,j)=(λ_(i,j ;1)+λ_(i,j ;2))/(λ_(i;1)+λ_(i;2))_(max), in a case ofspace diversity with two receive antennae of indices k=1 and k=2.

FIG. 7 gives a simple example of a procedure for determination of theactive set by the RRC stage 15A in the RNC 12. This procedure isexecuted for a given UE when the RNC, having the measurementCPICH_Ec/N0=A relative to a reference cell of the active set for whichthe CPICH_Ec/N0 or the SIR is maximal, receives a new CPICH_Ec/N0(i)value measured by the UE from a transceiver i of the monitored set (step60).

If the transceiver i is already in the active set EA (test 61), the RNCexamines a criterion for deletion of the transceiver from the active setrelative to the UE. This deletion criterion 62 relates to the globalreception energy according to the propagation channel between the mobileterminal and transceiver i, expressed by the quantity CPICH_Ec/N0(i),and it has a decreasing severity with the number β_(i) of propagationpaths detected by the UE from the other transceivers i′ of the activeset EA with a reception energy greater than a threshold

$\left( {\beta_{i} = {\sum\limits_{\underset{i^{\prime} \neq i}{i^{\prime} \in {EA}}}\alpha_{i^{\prime}}}} \right).$

Thus, the cell i will have more chances of being removed from the activeset when the number of energetic paths already procured by the otherpropagation channels of the active set is relatively high. In theexample in FIG. 7, examination of the criterion 62 consists in comparingthe difference A−CPICH_EC/N0(i) with a positive rejection threshold Srwhich is a decreasing function of the number β_(i). The cell i isremoved from the active set (step 63) when A−CPICH_EC/N0(i)>Sr and isretained otherwise (step 64).

If the transceiver i is not in the active set EA (test 61), the RNCexamines a criterion for admission of the transceiver into the activeset relative to the UE. This admission criterion 65 also relates to thequantity CPICH_Ec/N0(i) and has an increasing severity with the number βof propagation paths detected by the UE from the transceivers i′ of theactive set EA with a reception energy greater than a threshold

$\left( {\beta_{i} = {\sum\limits_{i^{\prime} \in {EA}}\alpha_{i^{\prime}}}} \right).$

Thus, the cell i will have fewer chances of being admitted to the activeset when the number of energetic paths already procured by thepropagation channels of the active set is relatively high. In theexample in FIG. 7, examination of the criterion 65 consists in comparingthe difference A−CPICH_EC/N0(i) with a positive admission threshold Sawhich is an increasing function of the number β. The cell i is removedfrom the active set (step 66) when A−CPICH_EC/N0(i)<Sa and is retainedotherwise (step 67).

FIG. 8 illustrates another example of a procedure for determining theactive set by the RRC stage 15A in the RNC 12. This procedure isexecuted for a given UE when the RNC receives a new suite of valuesCPICH_Ec/N0 measured by the UE from the transceivers of the monitoredset (step 69). The cells for which these values have been obtained arefirst placed in the order of decreasing CPICH_Ec/N0 (step 70) and theinteger variables k and i are initialized to zero (step 71).

The integer i serves to index a loop 72-76 the first step of which 72consists in placing the cell i in the active set relative to the UE inquestion. At the time of the first iteration, this involves placing inthe active set the cell for which the measurement CPICH_Ec/N0(0) ismaximal. In the following step 73, the integer k is increased by thenumber α_(i) of propagation paths of the physical channel of cell i forwhich a reception energy greater than a determined threshold has beendetected by the UE. This number α_(i) is supplied directly by the UE ordeduced by the RNC from the measurements λ_(i,j), μ_(i,j) or ρ_(i,j)uploaded by the UE.

The integer k is then compared with a parameter M in test 74. If k≧M,the RNC estimates that a sufficient number of energetic paths is alreadycovered by the cells of the active set such that it disables insertionof new cells by leaving the loop 72-76. If k<M, the integer i isincremented by one unit in step 75, then an admission criterion isexamined in step 76. In the example in FIG. 8, examining the criterion76 consists in comparing the difference CPICH_Ec/N0(0)−CPICH_Ec/N0(i)with a positive admission threshold Sa which may be an increasingfunction of the number k of paths already taken into consideration (orthe number i of cells already placed in the active set). The algorithmadmits the cell i into the active set by returning to step 72 whenCPICH_Ec/N0(0)−CPICH_Ec/N0(i)<Sa. Otherwise, the cell i and thesubsequent cells of the monitored set do not satisfy the admissioncriterion, so execution of the algorithm ends.

The values of the thresholds Sa(k) and of the parameter M can be chosenby the operator when configuring the radio network. They can also beadaptive. The parameter M may also depend on the capabilities of the UE,particularly the number of fingers in the rake receiver, indicated tothe RNC in the context of the RRC connection.

Naturally, a procedure such as that in FIG. 7 or 8 may relate toparameters other than the CIPCH_Ec/N0, for example the RSCPs and/or andSIRs. On the other hand, these procedures are only examples, given thata great diversity of insertion/deletion strategies for the active setmay be applied by the RNC using the parameters representative of theenergy distribution in the propagation profiles, such as the previouslydescribed α_(i), λ_(i,j) , μ_(i,j) or ρ_(i,j).

In addition, other algorithms, depending on the same types of parametersrepresentative of the energy distribution in the propagation profiles,may be used in the RNC, in particular to adjust the transmission powerof the transceivers of the active set in relation to a mobile terminal,with a view to balancing the downlink power transmitted by those fixedtransceivers (cf. section 5.2 of technical specification TS 25.214,“Physical Layer procedures (FDD)” version 3.6.0, published by the 3GPPin March 2001). The way in which the RNC controls the Nodes B to supplythem with the required balancing parameters is described in section8.3.7 of technical specification 3G TS 25.433 aforementioned. The “Pref”parameter, invoked in said section, can be adjusted cell by cell tocontrol the distribution of power over all the transceivers of theactive set. Here again, many strategies of power control may appear.

As an example, in a case in which the active set comprises two fixedtransceivers corresponding respectively to spreading codes with indicesi=1 and i=2, the RNC has the numbers α_(i) of paths having a receptionenergy greater than a threshold, as well as the total number β of pathsin question (β=α₁+α₂). It can moreover have communicated to it theattenuation (“pathloss” for each transceiver i by means of the“MEASUREMENT CONTROL” and “MEASUREMENT REPORT” messages of the RRCprotocol. This attenuation parameter, in dB, is the difference betweenthe transmission power on the primary CPICH by the transceiver i and theparameter CPICH_RSCP measured by the UE (see section 10.3.7.38 oftechnical specification 3G TS 25.331 aforementioned). The RNC may thenfix the power balancing parameters according to these attenuations andthe α_(i), for example in the following manner:

-   -   if the attenuations and the α_(i) are similar between the two        transceivers in question, the power is distributed equally        between the two transmitters,    -   if the α_(i) are similar whereas the attenuations are        substantially different between the two transceivers in        question, the power adjustment parameters are fixed so as to        transmit more strongly from the best transceiver (the lowest        pathloss). So, with α₁=α₂=3 and for a dissymmetry of 3 dB        between the two attenuations, a simulation has shown that the        power should be transmitted typically at 90% by the transceiver        thus favored and at 10% by the other transceiver, which        corresponds to a difference of approximately 10 dB on        transmission. Another simulation based on the hypotheses α₁=α₂=2        and a dissymmetry of 3 dB between the two attenuations has given        as typical values of power distribution between the two        transceivers 75%, to the benefit of the favored transceiver,        compared with 25% for the other transceiver,    -   if the attenuations are similar but the α_(i) are substantially        different between the two transceivers. in question, the power        adjustment parameters are fixed to favor also transmission from        the best transceiver (the highest α_(i)),    -   if the attenuations and the α_(i) are all dissimilar and lead to        choosing the same “best” transceiver, the imbalance of power        will then be further accentuated (at the limit by transmitting        at zero power on the least good transceiver),    -   if the attenuations and the α_(i) are both dissimilar and lead        to opposite choices for the same “best” transceiver, adjustments        can be applied that balance the transmission power or favor one        or other of the two criteria.

In all cases, the variations in power to be applied may be determined inan empirical manner with the aid of simulations. We then obtain aconversion table giving the transmission power adjustment parameters tobe sent to each of the transceivers according to the various attenuationvalues and α_(i) for each transceiver. Once constituted, this conversiontable may be stored in the RNC 12. The latter may use it after analyzingthe measurements uploaded to it in order to send to each transceiver theappropriate parameters for adjusting their transmission power.

Another use of parameters representative of the energy distribution inthe propagation profiles is described below, although many otherexamples may be envisaged. It involves the determination of the physicalchannel or channels to be used for communication between a mobileterminal and a given fixed transceiver, as well as their format. Asexplained above, a communication channel has specific features accordingto its format. The various formats that exist are assembled in Table ofsection 5.3.2 of the aforementioned technical specification 3G TS25.211. One of the important. features of a communication channel is itsspread factor SF, as explained above. The higher a channel's SF, thelower the bit rate that it offers. But at the same time, the higher achannel's SF, the longer a symbol's duration, hence better resistance tointerference, particularly between symbols.

Inter-symbol interference occurs when the time difference between thesignificant paths of the impulse response of the propagation channelexceeds the duration of a symbol, that is the duration of a chipmultiplied by the SF.

As was described previously, the receiver can transmit to the radionetwork controller RNC a time indication for certain paths which may beused to characterize the distribution over time of the paths detected bythe receiver during the duration of a symbol. It may also transmitrelative information giving for example the time separating two givenpaths, for example the two highest energy paths, over a receptionperiod. In all cases, the RNC, at the time of the processing of themessages sent by the mobile terminal or by the fixed transceiver, canextract from them a duration between two propagation paths, particularlythe maximum time difference between the paths signaled. It then comparesthis duration with that of a symbol over the current communicationchannels. On the basis of this comparison, the RNC can decide to chooseto modify the current communication channels and replace them with oneor more communication channels with different SFs. A similar process mayalso be carried out, not during a communication, but upon itsinitialization, when the radio resources are allocated.

To illustrate this general principle, let us consider a communicationchannel with SF 8 used at a given moment between a mobile terminal and afixed transceiver. For example, this is a number 15 format channelaccording to the coding in technical specification 3G TS 25.211.According to the above table 11, the channel can. transport 128+488=608data bits in a time slot. The duration of a symbol over this channel isapproximately 2 μs. If the measurements uploaded to the RNC show thatthe highest energy echoes are more than 2 μs apart (the difference inlength of the corresponding paths is greater than approximately 600 m),the RNC knows that inter-symbol interference (ISI) will occur. Tocounter this interference, while ensuring the required service, the RNCmay choose to use, by replacing this communication channel with twoother channels of SF 16, for example of No. 14 format (multicodetransmission). Communication is then also distributed between the twochannels. These channels have a symbol duration of approximately 4 μswhich severely restricts the ISI without the need to equip the receiverwith a complex equalizer. The number of payload data bits on each ofthese channels is 56+232=288 bits, or 576 bits for both channelstogether. The resultant bit rate is therefore slightly less with the twoSF 16 channels, which is due to the repetition of the bits of the DPCCHto the detriment of the information bits of the DPDCH. The difference inbit rate on the DPDCH is however reduced (by approximately 5%) and willnot, in many cases, prevent the required service being offered.

The converse case is also interesting since it may be used to avoidtransmitting in multicode when the RNC ascertains that the pathscorresponding to the uploaded profile measurements are distributed overa shorter duration than the symbol time of a channel of half the SF. Ifthe communication polls several channels of high SF, the number of rakereceiver fingers used is that much higher and risks, in the case of amobile terminal containing typically six fingers, leaving no fingersavailable particularly for listening to other fixed transmitters. It istherefore particularly advantageous in such a case to reconfigure themobile terminal and transceiver concerned so that they use a singlechannel of lower SF, for example half, to transport their communication,thereby also increasing the communication bit rate.

Transmission by the RNC of the channels to be used by the mobileterminal is carried out according to the RRC protocol as explained inthe aforementioned technical specification 3G TS 25.331, using a channelsetup or reconfiguration command: “Radio bearer setup”, “Radio bearerreconfiguration” or “Physical channel reconfiguration”. Each of thesemessages contains an information element called “Downlink informationfor each radio link” (see paragraph 10.3.6.27 of 3G TS 25.331). Thismessage itself contains an information element called “Downlink DPCHinfo for each RL” (see paragraph 10.3.6.1 of 3G TS 25.331). The lattermessage contains a number of information elements for characterizing thechannels to be used. Among these information elements there are thedownlink channel codes (values between 1 and <maxDPCH-DLchan>), thespread factors and the associated scrambling codes. On receipt of thismessage, the mobile terminal is capable of using the channel or channelsidentified and transmitted by the RNC.

According to the RRC protocol, the mobile terminal may also indicate tothe RNC its capabilities in terms of downlink channel support. This isdone using the “UE capability information” message (see paragraph10.2.56 of 3G TS 25.331), containing an information element “UE radioaccess capability” (see paragraph 10.3.3.42 of 3G TS 25.331) pointing inturn to the “Physical channel capability” (see paragraph 10.3.3.25 of 3GTS 25.331). For example, it is via this channel that the mobileindicates to the RNC the number of physical channels it supportssimultaneously. Thus the RNC bases its choice of channel allocationaccording to the effective capabilities of the mobile terminal.

Transmission by the RNC of the channels to be used by the fixedtransceiver is carried out according to the NBAP protocol, as explainedin the aforementioned technical specification 3G TS 25.433, using achannel setup or reconfiguration command: “Radio link set up request” or“Radio link reconfiguration prepare”. Each of these messages contains aninformation element called “FDD DL code information” (see paragraph9.2.214.a of 3G TS 25.433). The latter comprises a field called “FDD DLCode Information” containing, as previously, a list of channel codes tobe used by the fixed transceiver from a list of values (from 1 to<maxDPCH-DLchan>), while making reference to the scrambling codes and tothe associated spread factors.

It should be noted, in cases where several RNCs are involved in thecommunication, that the configuration command, that is the channelallocation command, can be sent to the transceiver by the DRNC, whereasit is always the SRNC that sends the configuration command to the mobileterminal.

1-63. (canceled)
 64. A method of controlling radio resources assignedfor communication between a mobile terminal and a cellular radioinfrastructure, the infrastructure comprising at least one radio networkcontroller and at least one fixed transceiver, the method comprising:determining a distribution of energy over time for at least onecommunication channel representing multiple propagation paths of at theleast one communication channel between the at least one fixedtransceiver and a mobile station; transmitting information indicative ofthe distribution of energy over time for the at least one communicationchannel to the radio network controller; processing the informationindicative of the distribution of energy over time for the at least onecommunication channel at the radio network controller to determineparameters to be used for the at least one communication channel betweenthe at least one fixed transceiver and the mobile station.
 65. A methodas defined in claim 64, wherein the distribution of energy over time forthe at least one communication channel is a channel impulse response.66. A method as defined in claim 64, wherein the step of processing theinformation indicative of the distribution of energy over time for atthe least one communication channel to determine parameters to be usedfor the at least one communication channel comprises processing theinformation indicative of the distribution of energy over time for theat least one communication channel to determine a format to be used forthe at least one communication channel between the at least one fixedtransceiver and the mobile station.
 67. A method as defined in claim 66,wherein the format is defined by at least one of the followingparameters: channel bit rate; channel symbol rate: spreading factor;bits per slot; dedicated physical data channel (DPDCH) bits per slot;dedicated physical control channel (DPCCH) bits per slot; andtransmitted slots per radio frame.
 68. A method as defined in claim 67,wherein the format is defined by all of the parameters listed in claim3.
 69. A method as defined in claim 67, wherein the DPDCH bits per slotcomprise bits per slot in a first data channel and bits per slot in asecond data channel.
 70. A method as defined in claim 67, wherein theDPCCH bits per slot comprise transmit power control (TPC) bits,transport format combination indicator (TFCI) bits and pilot bits perslot.
 71. A method as defined in claim 64, further comprising processingthe information indicative of the distribution of energy over time forthe at least one communication channel to determine if the communicationchannel is to be split into at least two communication channels to beused between the at least one fixed transceiver and the mobile station.72. A method as defined in claim 64, wherein: the step of determining adistribution of energy over time for at least one communication channelcomprises determining distributions of energy over time for at least twochannels representing multiple propagation paths between at least twofixed transceivers and the mobile station; the step of transmittinginformation indicative of the distribution of energy over time for theat least one communication channel to the radio network controllercomprises transmitting information indicative of the distributions ofenergy over time for the at least two channels to the radio networkcontroller; and the step of processing the information indicative of theat least one distribution of energy over time for the at least onecommunication channel at the radio network controller comprisesprocessing the information indicative of the distributions of energyover time for the at least two channels to determine parameters forbalancing transmission power settings for the at least two fixedtransceivers.
 73. A method as defined in claim 72, wherein the step ofprocessing the information indicative of energy distributions for the atleast two channels at the radio network controller comprises processingthe information indicative of energy distributions for the at least twochannels to determine a preferred active set of transceivers to be usedfor communication with the mobile station.
 74. A radio networkcontroller for a wireless communication system comprising at least onefixed transceiver, the radio network controller comprising: a receiveroperable to receive a distribution of energy over time for at least onecommunication channel representing multiple propagation paths of atleast one communication channel between the at least one fixedtransceiver and a mobile station; and a processor operable to processthe information indicative of the distribution of energy over time forthe at least one communication channel at the radio network controllerto determine parameters to be used for the at least one communicationchannel between the at least one fixed transceiver and the mobilestation.
 75. A radio network controller as defined in claim 74, whereinthe distribution of energy over time is a channel impulse response. 76.A radio network controller as defined in claim 74, wherein the processoris operable to process the information indicative of the distribution ofenergy over time for at least one communication channel to determineparameters to be used for the at least one communication channel todetermine a format to be used for the at least one communication channelbetween the at least one fixed transceiver and the mobile station.
 77. Aradio network controller as defined in claim 76, wherein the format isdefined by at least one of the following parameters: channel bit rate;channel symbol rate: spreading factor; bits per slot; dedicated physicaldata channel (DPDCH) bits per slot; dedicated physical control channel(DPCCH) bits per slot; and transmitted slots per radio frame.
 78. Aradio network controller as defined in claim 77, wherein the format isdefined by all of the parameters listed in claim
 77. 79. A radio networkcontroller as defined in claim 77, wherein the DPDCH bits per slotcomprise bits per slot in a first data channel and bits per slot in asecond data channel.
 80. A radio network controller as defined in claim77, wherein the DPCCH bits per slot comprise transmit power control(TPC) bits, transport format combination indicator (TFCI) bits and pilotbits per slot.
 81. A radio network controller as defined in claim 74,wherein the processor is further operable to process the informationindicative of the distribution of energy over time for the at least onecommunication channel to determine if the communication channel is to besplit into at least two communication channels to be used between the atleast one fixed transceiver and the mobile station.
 82. A radio networkcontroller as defined in claim 74, wherein: the receiver is operable toreceive distributions of energy over time for at least two communicationchannels representing multiple propagation paths between at least twofixed transceivers and the mobile station; and the processor is operableto process the information indicative of the distributions of energyover time for the at least two communication channels to determineparameters for balancing transmission power settings for the at leasttwo fixed transceivers.
 83. A radio network controller as defined inclaim 82, wherein the processor is operable to process the informationindicative of energy distributions for the at least two communicationchannels to determine a preferred active set of transceivers to be usedfor communication with the mobile station.
 84. A method of operating aradio network controller for a wireless communication system comprisingat least one fixed transceiver, the method comprising: receivinginformation indicative of a distribution of energy over time for atleast one communication channel representing multiple propagation pathsof at least one communication channel between the at least one fixedtransceiver and a mobile station; and processing the informationindicative of the distribution of energy over time for the at least onecommunication channel at the radio network controller to determineparameters to be used for the at least one communication channel betweenthe at least one fixed transceiver and the mobile station.
 85. A methodas defined in claim 84, wherein the distribution of energy over time forthe at least one communication channel is a channel impulse response.86. A method as defined in claim 84, wherein processing the informationindicative of the distribution of energy over time for the at least onecommunication channel to determine parameters to be used for the atleast one communication channel comprises processing the informationindicative of the distribution of energy over time for the at least onecommunication channel of the communication channel to determine a formatto be used for the at least one communication channel between the atleast one fixed transceiver and the mobile station.
 87. A method asdefined in claim 84, wherein the format is defined by at least one ofthe following parameters: channel bit rate; channel symbol rate:spreading factor; bits per slot; dedicated physical data channel (DPDCH)bits per slot; dedicated physical control channel (DPCCH) bits per slot;and transmitted slots per radio frame.
 88. A method as defined in claim87, wherein the format is defined by all of the parameters listed inclaim
 24. 89. A method as defined in claim 87, wherein the DPDCH bitsper slot comprise bits per slot in a first data channel and bits perslot in a second data channel.
 90. A method as defined in claim 87,wherein the DPCCH bits per slot comprise transmit power control (TPC)bits, transport format combination indicator (TFCI) bits and pilot bitsper slot.
 91. A method as defined in claim 84, further comprisingprocessing the information indicative of the distribution of energy overtime for the at least one communication channel to determine if thecommunication channel is to be split into at least two communicationchannels to be used between the at least one fixed transceiver and themobile station.
 92. A method as defined in claim 84, wherein: receivinginformation indicative of a distribution of energy over time for the atleast one communication channel comprises receiving informationindicative of distributions of energy over time for the at least twocommunication channels representing multiple propagation paths betweenat least two fixed transceivers and the mobile station; and processingthe information indicative of the at least one distribution of energyover time for the at least one communication channel comprisesprocessing the information indicative of the distributions of energyover time for the at least two communication channels to determineparameters for balancing transmission power settings for the at leasttwo fixed transceivers.
 93. A method as defined in claim 92, comprisingprocessing the information indicative of energy distributions for the atleast two communication channels to determine a preferred active set oftransceivers to be used for communication with the mobile station.
 94. Amobile terminal for a wireless communication system, the mobile terminalcomprising: a receiver operable to receive signals from at least onefixed transceiver over at least one communication channel havingmultiple propagation paths; a processor operable to determine adistribution of energy over time for the at least one communicationchannel; and a transmitter operable to transmit information indicativeof the at least one distribution of energy over time for the at leastone communication channel to an infrastructure of the wirelesscommunication system.
 95. A mobile terminal as defined in claim 94,wherein the distribution of energy over time for the at least onecommunication channel is a channel impulse response.
 96. A mobileterminal as defined in claim 94, wherein: the receiver is operable toreceive signals from at least two fixed transceivers; the processor isoperable to determine distributions of energy over time for at least twocommunication channels representing multiple propagation paths betweenthe at least two fixed transceivers and the mobile station; and thetransmitter is operable to transmit information indicative of the atleast two distributions of energy over time for the at least twocommunication channels to the infrastructure of the wirelesscommunication system.
 97. A method of operating a mobile terminal for awireless communication system, the method comprising: receiving signalsfrom at least one fixed transceiver over at least one communicationchannel having multiple propagation paths; determining a distribution ofenergy over time for the at least one communication channel; andtransmitting information indicative of the at least one distribution ofenergy over time for the at least one communication channel to aninfrastructure of the wireless communication system.
 98. A method asdefined in claim 97, wherein the distribution of energy over time forthe at least one communication channel is a channel impulse response.99. A method as defined in claim 97, comprising: receiving signals fromat least two fixed transceivers; determining distributions of energyover time for at least two communication channels representing multiplepropagation paths between the at least two fixed transceivers and themobile station; and transmitting information indicative of the at leasttwo distributions of energy over time for the at least two communicationchannels to the infrastructure of the wireless communication system.100. A wireless communication system, comprising: at least one fixedtransceiver; at least one mobile terminal operable: to receive signalsfrom the at least one fixed transceiver; to determine a distribution ofenergy over time for at least one communication channel representingmultiple propagation paths of at least one communication channel betweenthe at least one fixed transceiver and the mobile station; and totransmit information indicative of the distribution of energy over time;and a radio network controller operable: to receive the informationindicative of the distribution of energy over time; and to process theinformation indicative of the distribution of energy over time for theat least one communication channel to determine parameters to be usedfor the at least one communication channel between the at least onefixed transceiver and the mobile station.
 101. A wireless communicationsystem as defined in claim 100, wherein the distribution of energy overtime is a channel impulse response.
 102. A wireless communication systemas defined in claim 100, wherein the radio network controller isoperable to process the information indicative of the distribution ofenergy over time for the at least one communication channel to determineparameters to be used for the at least one communication channelcomprises processing the information indicative of the distribution ofenergy over time for at the least one communication channel to determinea format to be used for the at least one communication channel betweenthe at least one fixed transceiver and the mobile station.
 103. Awireless communication system as defined in claim 100, wherein the radionetwork controller is operable to process the information indicative ofthe distribution of energy over time for at least one communicationchannel to determine if the communication channel is to be split into atleast two communication channels to be used between the at least onefixed transceiver and the mobile station.
 104. A wireless communicationsystem as defined in claim 100, wherein: the wireless communicationsystem comprises at least two fixed transceivers; the at least onemobile terminal is operable: to receive signals from the at least twofixed transceivers; to determine distributions of energy over time forat least two channels representing multiple propagation paths between atleast two fixed transceivers and the mobile station; and to transmitinformation indicative of the distributions of energy over time for theat least two channels; and the radio network controller is operable: toreceive the information indicative of the distributions of energy overtime for the at least two channels; and to process the informationindicative of the distribution of energy over time for the at least onechannel to determine parameters to be used for the at least onecommunication channel between the at least one fixed transceiver and themobile station to determine parameters for balancing transmission powersettings for the at least two fixed transceivers.
 105. A wirelesscommunication system as defined in claim 104, wherein the radio networkcontroller is operable to process the information indicative of energydistributions for the at least two channels to determine a preferredactive set of transceivers to be used for communication with the mobilestation.